Plug connector with switch for auxiliary starting circuit



E. B. SLEETER PLUG CONNECTOR WITH SWITCH FOR AUXILIARY STARTING CIRCUIT Filed April 9, 1959 fill/l/ll/l/V/l/ 4 Oct. 25, 1960 m m m5 wfi w W -H. I

Unite PLUG CONNECTOR WITH SWITCH FOR AUXIL- IARY STARTING CIRCUIT Filed Apr. ,9, 1959, Set. No. 805,185

7 Claims. (Cl. Mill-51.09)

This invention relates to electrical plug-in connectors, and has as its general object to provide an electrical plug having prongs adapted to be received in an outlet re ceptacle, and having means whereby an auxiliary circuit may be momentarily energized concurrently with insertion of the plug into a receptacle.

Certain types of electrical devices have auxiliary circuits that must be energized for a short time when the device is started, concurrently with initial energizat-ion of the main circuit. A fluorescent light, for example, has a starting circuit that must be energized briefly when the light is turned on, and which is then turned off after the lamp has been fired up by an initial surge of relatively high voltage, whereupon the lamp continues to operate on its normal rated line voltage. Some types of electric motors also have auxiliary windings in circuits which are closed for only a few seconds during starting and which are then opened after the motor has come up substantially to its rated speed.

In the past, the auxiliary starting circuits of electrical devices such as non-automatic washing machines, home Workshop tools, ironers, fans and other such appliances have been controlled by switches, usually of the automatic type, although manually operable switches could be used for that purpose.

Inasmuch as the main and auxiliary circuits of these devices must, of necessity, be selectively controlled, it was heretofore impossible to employ their standard plug-in connectors for that purpose. Such plug-in connectors merely enabled such devices to be connected with or .completely disconnected from a source of current.

It is therefore an object of this invention to provide a special power cord plug for an electrical device having an auxiliary circuit, which plug incorporates means that enables the auxiliary circuit to be controlled as ,a consequence of insert-ion of the plug into an outlet receptacle and thus eliminates the need for a separate switch of the type heretofore used to control the auxiliary circuit of the device.

More specifically, it is an object of this invention to provide a plug-in connector for an electrical device having main and auxiliary circuits, which connector incorporates a normally open switch for controlling the auxiliary circuit, and has body members that are adapted to be moved relative to one another, as a consquence of the manual application of force to one of said members incidental to plugging of the connector into a standard power outlet receptacle, to effect closing of the switch and completion of the auxiliary circuit for a period of time determined by the duration of said manually applied force.

Another object of this invention is to provide a male electrical plug of the type adapted for attachment tothe power cord of an electrical applicance and intended to be received in a standard outlet receptacle, which plug has a shell telescopingly embracing its body and movable back and forth relative thereto, said shell being adapted to be gripped for manipulation of the plug during insertion of the plug into an outlet receptacle and providing an actutates Patent the like.

ator for a normally open switch in the plug body, where by the switch is closed in consequence of forward movement of the shell relative to the body, as when forward force is applied to the shell during insertion of the plug into a receptacle.

Another object of this invention resides in the provision of a plug having the features set forth in the preceding statement of object, and wherein an element of the switch cooperates with the shell to confine the latter against displacement off of the plug body.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure l is a longitudinal sectional view of the electrical plug of this invention, showing the same in its normal condition;

Figure 2 is a view similar to Figure l but showing the plug with its outer shell in the position to which it is moved during insertion of the plug into an outlet receptacle, and in which the shell eifects closure of an auxiliary starting circuit; and

Figure 3 is a front end view of .the plug.

Referring now more particularly to the accompanying drawing, the numeral 5 designates generally a male .electrical .connector plug of this invention having a body 6 from which a pair of prongs 7 and 8 project forwardly to be received in a standard outlet receptacle 9. The

' body of the plug comprises a hollow fixed body member 10 comprising a housing having mounting means 11 therein to which inner portions of the prongs are secured and which also supports a normally open switch 12 for controlling .energization of an auxiliary starting circuit or The body member encloses the switch and the rear portions of the prongs, as well as the connections of conductors 13, 14 and 15 to the prongs and switch.

I Theplug body also includes a shell 16 that telescopingly embraces the body member 10 to provide a gripping portion .or handle for the plug by which it may be manipulated, and which also serves as an actuator for the switch 12 being movable back and forth relative to the body member.

More specifically, the hollow body member 10, which may be molded of plastic or otherwise formed of insulating material, is substantially cup-shaped, having a tubular side wall 17 and a concentric bored boss 18 in its bottom wall 19 through which pass the conductors 13, 14 and 15 comprising the cord to which the plug is connected. The mounting means 11 for the prongs and the switch may be formed as a block or pad of insulating material project- .ing inwardly from the side wall 17 of the body member and preferably integral therewith. The strips of metal which comprise the prongs are secured to the mounting paid as by means of nylon rivets 20, and are held thereby in fixed, laterally spaced apart relationship, with their front ends projecting through a cover 21 that closes the front of the fixed body member. One prong 7 has its rear end portion flatwise fastened to the mounting pad, and has a screw 23 threaded into its medial portion, between the pad and the cover 21, to provide a terminal to which one of the conductors 13 may be connected. The other prong 8 has its medial portion confined in a slot in the pad, and it projects both forwardly and rear- 3 wardly beyond the pad, its front end portion extending through the cover 21 and its rearwardly pro ecting portion 25 having a screw 26 threaded thereinto to provide a terminal for the conductor 14. To conserve space and permit the switch 12 as well as the prongs to be accommodated within the hollow body, the prong 8 is bent adjacent to the pad, as at 27, to offset its forward portion laterally outwardly.

Just forward of the offset bend 27, but behind the cover 21, the prong 8 has a rivet 28 or the like affixed to it to provide the stationary contact member of the switch 12, while a similar rivet 30, carried at the free end of a spring arm 31, provides the cooperating movable contact 'of the switch. The other end portion of the spring arm 31 is flatwise clamped against the face of the mounting pad remote from the prong 7 by means of a metal terminal strip 33 that fiatwise overlies the fixed end portion of the spring arm and is held in place by rivets 20 extending through both the spring arm and the terminal strip. The rear portion of the terminal strip projects behind the mounting pad and has a screw 34 threaded thereinto to provide a terminal to which the conductor 15 may be connected.

The front portion of the spring arm is bent at an obtuse angle to the fixed rear end portion thereof and projects obliquely forwardly and laterally outwardly, through a lengthwise extending slot 35 in the side wall 17 of the body member 10, opening to the front thereof. The movable contact 30 at the free end of the spring arm is normally held spaced from the stationary contact 28 by the spring arm, but the shell 16 serves as an actuator by means of which the spring arm may be swung laterally inwardly, against its bias, to bring the contacts 28 and 30 into engagement with one another and thus complete a circuit through the conductors 14 and 15.

The shell 16, which may be molded of plastic insulating material, is substantially cup-shaped, with a cylindrical side wall 36 that closely slidably embraces the side wall 17 of the fixed body member 10, and the shell has a bore 38 in its bottom wall 39 through which projects the boss 18 on the rear end of the housing member. Projecting inwardly from the side wall of the shell, near the front thereof, is an integral protuberance 40 which projects into the interior of the body member through the slot 35 and has a rearwardly and inwardly inclined front surface that is adapted to engage the obliquely disposed free end portion of the spring arm 31.

It will be apparent that as the shell is moved forwardly on the body member 10, the protuberance 40 wedgingly cams the spring arm inwardly to engage the movable contact against the stationary one. The shell is preferably somewhat longer than the body member 10, so that the latter is substantially completely surrounded by the shell, and therefore the shell presents itself as a gripping portion of the plug by which the same is naturally manipulated when it is engaged in an outlet receptacle.

Hence, the forward force exerted upon the shell incident to seating the prongs of the plug in the slots of an outlet receptacle causes the shell to effect closure of the switch; and so long as forward pressure is maintained on the shell while the plug is in the socket, the switch will remain closed, energizing the auxiliary circuit that includes the conductors 14 and 15. However, as soon as the shell is released it moves rearwardly in response to the bias of a coiled compression spring 42 confined between the bottom wall 19 of the body member and the bottom wall 39 of the shell and piloted on the boss 18.

The shell is assembled over the body member by merely sliding it forwardly thereover after the prongs and switch are installed. To admit the protuberance 40 the slot 35 I in the body member side wall extends rearwardly through the bottom wall of the body member. The shell is held .in-place on the body member by means of an integral rearwardly facing abutment 44 on the front of the shell,

projecting into the slot 35 in the body member, which is engaged by the front end of the spring arm to define the most rearward position to which the shell can move in response to the bias of the compression spring 42. As the shell is being assembled onto the body member the abutment 44 readily cams its way past the spring.

Since a relatively light spring arm may be used, and it may be desirable in some cases to have the compression spring 42 exert a substantial rearward biasing force on the shell, an additional stop to prevent rearward displacement of the shell off of the body member may be desired, and this may be readily provided by means of a short screw 47 threaded into the side wall of the shell after the shell has been telescoped onto the body member and projecting into a forwardly opening slot 48 in the body member side wall 17. The bottom of the slot 48 is then engaged by the screw 47 when the shell moves to its most rearward position relative to the body member.

From the foregoing description taken together with the accompanying drawing, it will be apparent that this invention provides an electrical connector plug of the type having prongs adapted to be received in any standard outlet receptacle, which plug incorporates a normally open switch and an actuator for the switch comprising a shell that movably embraces the plug body and provides a gripping portion for the plug, wherein the switch is actuated to a closed position in consequence of movement of the shell in one direction relative to the plug body when the plug is inserted into an outlet receptacle, closing an auxiliary starting circuit or the like, and wherein the switch returns to its normally open position when the shell is released.

What is claimed as my invention is:

1. In an electrical connector plug of the type having prongs engageable in slots in an electrical outlet receptacle in order to establish an energizing circuit through conductors connected with the prongs and with an electrical device: a plug body comprising relatively fixed and movable body members which define a shell for enclosing portions of the prongs and of conductors connected with them, the fixed body member having means securing the prongs thereto with the prongs projecting endwise forwardly therefrom, and the movable body member being movable relative to the fixed body member in directions parallel to the prongs and providing a gripping portion for the plug by which the same may be manipulated dur ing its insertion into a receptacle; cooperating fixed and movable switch contact members carried by the plug body, connectable with an auxiliary circuit in an electrical device, the movable contact member being biased away from engagement with the fixed contact member; means on the movable body member providing a motion transmitting connection between the movable body member and the movable contact member whereby the latter is moved into circuit making engagement with the fixed contact member upon forward movement of the movable body member relative to the fixed body member, as during insertion of the plug into a receptacle; and biasing means reacting between the fixed and movable body members to urge the movable body member rearwardly, so that upon release of the movable body member after insertion of the plug into a receptacle the relatively movable contact member will be separated from the fixed contact member in response to the bias on the movable contact member, to open the auxiliary circuit.

2. In an electrical connector plug of the type having prongs engageable in slots in an electrical outlet receptacle in order to establish an energizing circuit through conductors connected with the prongs and with an electrical device: a plug body comprising a relatively fixed body member and a body member movable in opposite directions relative to the fixed body member and cooperating therewith to define a shell for enclosing portions of the prongs and of conductors connected with them, the fixed body member having means securing the prongs thereto with the prongs projecting endwise therefrom, and the movable body member providing a gripping portion by which the plug may be manipulated during its insertion into a receptacle; cooperating fixed and movable switch contact members carried by the plug body, one of said contact members being connectable with one of the prongs and the other contact member being connectible with an auxiliary circuit in an electrical device, the movable contact member being biased away from engagement with the fixed contact member; means on the movable body member providing a motion transmitting connection between the movable body member and the movable contact member whereby the latter is moved into circuit making engagement with the fixed contact member, against its bias, upon movement of the movable body member in one direction relative to the fixed body member, as during insertion of the plug into a receptacle; and biasing means reacting between the fixed and movable body members to urge the movable body member in the opposite direction, so that upon release of the movable body member after insertion of the plug into a receptacle the relatively fixed and movable contact members will be separated, to open the auxiliary circuit. 7

3. In an electrical connector plug of the type having prongs engageable in slots in an electrical outlet receptacle in order to establish an energizing circuit through conductors connected with the prongs and with an electrical device: a body member comprising a housing and means in the housing holding the prongs in fixed, spaced apart relationship, with portions of the prongs projecting for- Wardly from the housing, the housing providing an enclosure for the rear portions of the prongs and their connections to conductors; a fixed switch contact on one of said prongs, inside the housing; a spring arm secured at one end to said body member and having its other free end yieldingly movable toward and from said fixed switch contact; a movable switch contact carried by said spring arm for engagement with said fixed switch contact in consequence of movement of the free end of the spring arm toward the same, said movable switch contact being normally biased away from the fixed switch contact by the spring arm; a substantially cup-shaped shell concentrically embracing the body member and telescopingly movable back and forth relative to the body member, said shell providing a gripping portion for the plug by which the plug is adapted to be manipulated when it is inserted into a receptacle; a protuberance on said shell engageable with the spring arm through an aperture in the body member, and cooperable with the spring arm to urge the free end of the latter toward the fixed switch contact in consequence of forward movement of the shell relative to the body member, so that the switch contacts are engaged during insertion of the plug into a receptacle; and spring means reacting between the body member and the shell to bias the shell rearwardly relative to the body member, so that engagement between the switch contacts is terminated when the shell is released after the plug has been inserted into a receptacle.

4. The electrical connector plug of claim 3, further characterized by the fact that said spring arm projects obliquely forwardly and laterally outwardly relative to the body member; further characterized by the fact that said protuberance on the shell provides a rearwardly and inwardly inclined surface by which the spring arm is wedgingly swung toward the fixed switch contact in consequence of forward movement of the shell; and further characterized by a rearwardly facing abutment on the front of the shell, engageable with the front end of the spring arm to define the most rearward position to which the shell may be moved in response to the bias of said spring means.

5. In an electrical connector plug of the type having prongs engageable in slots in an electrical outlet receptacle in order to establish an energizing connection through conductors connected with the prongs and with an electrical device, and having a housing body in which the rear end portions of the prongs are'mounted and from which they project forwardly: means in the housing body, including relatively fixed and movable contacts, providing a normally open switch, one of said contacts being connected with one of the prongs, and the other contact being connectable with an auxiliary circuit of an electrical device; a forwardly and outwardly inclined leaf spring arm in the housing body by which the movable switch contact is carried; an actuator comprising a substantially cup-shaped shell telescoped over the housing body and movable back and forth relative thereto, said actuator having a protuberance engageable with the leaf spring through an aperture in the housing body to cam the leaf spring inwardly upon forward movement of the actuator relative to the housing body, as during insertion of the plug into a receptacle, and thereby move the movable switch contact into engagement with the fixed contact; and yieldable biasing means reacting between the housing body and the actuator to urge the latter rearwardly so that the switch means opens upon release of the actuator after insertion of the plug into a receptacle.

6. The electrical connector plug of claim 5, further characterized by an inwardly projecting rearwardly facing abutment on the front of the actuator engageable by the front end of the leaf spring arm to define the rearward limit of actuator movement relative to the housing body.

7. In an electrical connector plug of the type having prongs engageable in slots in an electrical outlet receptacle in order to establish an energizing circuit through conductors connected with the prongs and with an electrical device: a hollow plug body comprising a relatively fixed portion and a portion which is movable in opposite directions relative to the fixed portion and which is biased in one of said directions, said relatively fixed and movable portions cooperating to define a shell for enclosing portions of the prongs and of conductors connected with the prongs, the fixed portion of the body having means securing the prongs thereto with the prongs projecting endwise out of the shell, and the movable portion of the body being adapted to be manually gripped for insertion of the plug into a receptacle and to be moved in the other of its directions of motion during such insertion; cooperating fixed and movable switch contact members carried by the plug body, within the shell, the fixed contact member being secured to one of the prongs and the movable contact member being connectable with an auxiliary circuit in an electrical device and being biased away from engagement with the fixed contact member; and means on the movable body portion providing a motion transmitting connection between the movable body portion and the movable contact member whereby the latter is moved into circuit making engagement with the fixed contact member, against its bias, upon movement of the movable body member in said other direction relative to the fixed body member, as during insertion of the plug into a receptacle.

References Cited in the file of this patent UNITED STATES PATENTS 896,838 Klein Aug. 25, 1908 1,141,686 Jones June 1, 1915 2,088,355 Wehming July 27, 1937 2,672,532 Robinson Mar. 16, 1954 

